How membrane-bound organelles of eukaryotic cells maintain their identity and subcellular localization amidst an enormous input and outflow of membrane and protein is a central question in cell biology. Studies in this group have focused on this question and have sought to define the cellular and molecular mechanisms which underlie the organization and distribution of eukaryotic organelles. Particular attention has been paid to the Golgi complex which plays a fundamental role in the processing and sorting of protein moving through the secretory pathway. The Golgi complex in higher eukaryotes consists of stacks of flattened cisternae usually localized to the perinuclear region near the microtubular organizing center (MTOC). Recent studies have suggested this organization and positioning of the Golgi are controlled by dynamic processes. Tubulovesicular structures emerging from Golgi elements along microtubules, for example, enable adjacent Golgi stacks to communicate. In addition, reversible dispersal of Golgi elements occurs during microtubule disruption, mitosis and brefeldin A (BFA)-treatment. To further understand these processes and their relationship to the three-dimensional morphology and function of the Golgi we have generated Golgi protein chimeras containing the green fluorescent protein (GFP). Using these constructs to label Golgi complex in living cells, we have performed time-lapse imaging to examine the dynamics of the Golgi complex in under a variety of conditions. In addition, we have examined the diffusional mobility of the chimeras in interphase and mitotic cells. Results from these studies are providing new insights into mechanisms of Golgi protein retention and targeting.